Bottom drive pulper with stationary blades



Dec. 29, 1964 c. A. JOHNSON 3,163,353

BOTTOM DRIVE PULFER WITH STATIONARY BLADES Filed Dec. 18. 1961 FW(\\ I 4 km J CHARLES A JOHNSON BY PM PM ATTORNEYS United States. Patent 3,163,368 BGTTGM D PULPER WITH STATEQNARY ELADES Charles A. Johnson, Andover, Mass, assignor to John W. Bolton & ons, Inc, Lawrence, Mass, a corporation of Massachusetts Filed Dec. 18, 1961, Ser. No. 159,862 6 Claims. ((ll. 241-46) This invention relates to the art of defibering pulp, or broke, and particularly to an improved pulper of the bottom drive, round Walled or lobular walled type.

It has heretofore been proposed to provide a pulper in which a bottom drive, circulating impeller is encircled by an annular series of stationary blades, the blades serving as deflectors as in US. Patent No. 1,790,257 to Bakewell of Ian. 27, 1931. I

In this invention stationary blades define a circle around the impeller, and are at least co-extensive in height with the impeller vanes and the disc-like stream emitted by the impeller, but the blades are not deflectors. The stationary blades of this invention present a relatively narrow inner face to the efiluent flow path of the material which partially checks the flow and, therefore, partially reduces circulation. Each opposite side face of each blade extends along the flow path of the material, parallel to the normal tangential discharge of the impeller vanes to avoid checking or deflecting fiow but includes a plurality of continuous sharp edged ribs extending transversely to the flow path for scrubbing material advanced thereacross.

Thus the principal object of the invention is to provide stationary blades around a revolving impeller which tend to shear large fibre bundles and then to further disintegrate such fibre bundles by impact against ribs, flutes, corrugations or serrations on the tangentially arranged side faces of the blades without deflecting the bundles from the normal tangential flow path.

Another object of this invention is to increase the efficiency of bottom rotor pulpers by inter-posing upstanding stationary blades with ribbed faces in, and parallel to the effluent tangential flow path of the rotor thus reducing the cycle time from the start of pulping to the end of pulping from approximately thirty minutes to seventeen or eighteen minutes. V

A further object of the invention is to provide stationary blades around a rotating impeller, the blades having a rough or serrated side faces, tangentially arranged in alignment with the impeller discharge to avoid deflection thereof, but treating, disintegrating and performing work on fibre bundles in said tangential discharge.

Still another object of the invention is to provide stationary blades around a rotating impeller wherein the inner face of the blades is flat, narrow and normal to the direction of flow to partially check circulation while forming a shearing edge cooperative with the outer face of the impeller and wherein the side faces are tangentially arranged, sharply serrated and extend along the direction of flow to further treat, grate, vibrate and disintegrate the material.

Other objects and advantages of the invention will be apparent from the claims, the description of the drawing and from the drawing in which:

FIG. 1 is a plan view of the bottom of a bottom drive pulper showing the flow path of material and the stationary, ribbed blades of the invention,

FIG. 2 is an enlarged perspective view of the structure shown in FIG. 1, and

FIG. 3 is a still further enlarged perspeotiveview of one of the stationary, ribbed blades of the invention.

In FIGURES l and 2, 20 designates a pulper of any ice bottom toward the side wall, the material then ascending along the side wall, converging toward the centre and then descending down the axis of the impeller in a vortex for recirculation. Disintegnation of the fibre bundles in the material being pulped may be caused by what has been termed hydraulic shear, by impact with the walls of the A pulper or by vortical impact with the rotating impeller and in a typical two thousand pound commercial size pulper the cycle time is usually about thirty minutes.

The cycle time of such a pulper has been reduced to seventeen or eighteen minutes by the interposition of an annular series 30 of stationary blades such as 31 and 32, the blades defining a circle around the impeller 23. The series of blades 30 is close to the impeller 23 and spaced inwardly from the side wall 21 so that the blades are in the zone of maximum impact as the material to be pulped is discharged from the impeller.

Preferably the outer faces 33 of the vanes 24 and the inner faces 34 of the blades 31 or 32 are vertical and closely spaced to shear any fibre bundles passing there- 'between. The blades 31 and 32 include a base portion 35 which extends horizontally and includes a pair of apertures 36 and 37 for attachment bolts 38 and 39 which are threadedly fixed to the bottom wall 22. The base portion 35 is equal in height to the plate 41 of the impeller 23 and the blades 31 and 32 are co-extensive in height with the vanes 24 and with the disc-like stream of material emitted by the impeller.

The inner face 34 of each upstanding blade31 or 32 is vertical, flat and smooth and extends in a direction normal to the flow path of material discharged by the impeller, the flow path being normally tangential, relative to the impeller, as indicated by wavy arrows in FIG. 1. A sharp edge 42 of right angular cross section extends vertically along the side 43 of the inner face 34 which is presented to oncoming material to serve as a shear edge. The blades 31 and 32 do not extend radially but are angularly disposed at an angle of about 45 or more from a radial line passing through the centre of the impeller. Thus the inner face 34 is not uniformly spaced from the path of the outer faces 33 of the impeller but converges toward that path from the shearing edge 42 to the opposite side edge 44 of the face 34. The face 34, is therefore a narrow barrier or batfle perpendicularly across the path of the effluent material discharged by the impeller, thereby tending to halt fibre bundles while they are sheared while also slowing circulation slightly to avoid excessive and non productive vortical action.

The opposite side faces 50 and 51 of each blade, such as 31, are relatively broad and extend in the direction of the 'eflluent flow from the impeller and substantially parallel thereto. Preferably,.the side faces 50 and 51 are angularly disposed from a radial line through the centre or axis of impeller 23 at an angle of about 45 or more, this being about the angle of the flow'path of material discharged centrifugally by the impeller shown. Thus the side faces 59 and 51 are tangentially arranged relative to the impeller, and to its tangential discharge, and would have a negligible barrier, baffle or deflection function if smooth.

However, the side faces 50 and 51 are provided with scrubbing means 52 preferably in the form of a plurality of identical, continuous ribs such as 53 and 54,"separated by grooves .55, and extending transverselytof the flow path, or tangential discharge depicted by the wavy arrows.

Each rib 53 includes a sharp edge 56 and extends from I the relatively narrow free end 57 of theblade downwardlyindividual rib 54 as it follows the vortical circulation path set up in the pulper. The fluted, ribbed, serrated or corrugated faces of the blades 31 or 32 furnish additional work or treatment to the stock by adding a scrubbing, grating or vibrating action which tends to further disintegrate fibre bundles and separate or'loosen'the fibres therein. t

It has been found that blades equal in number'to the vanes on the impeller and spaced apart as shown, give excellent results although it will be obvious that more blades may be used if it is desired te increase thescrubbing and distintegrating effect of theblades. 7 It should be noted that the scrubbing means 52 on the stationary blades is co-extensive in height with the impeller vanes and with the annular disc-like stream discharged by the impeller and positioned to receive the maximum impact of the effluent stream. Also that the increased width of the face 34 at the base end of the blades presents a wider barrier to the heavier fibre bundles in the stock, travelling on the outside of the vortical circulatory path thereby deterring such bundles for shearing action by the edge 42.

The side faces 50 and 51 of each blade 31 or 32 are angularly disposed to axial planes passing through the impeller axis and the side faces are straight in their cross axial planes. Thus the material tangentially discharged by the impeller is bothtangentially received and tangentially discharged by the blades without deflection.

I claim:

1. In a pulper of the type having a tank, a material cir-.

culating impeller therein having vanes tangentially discharging material in an annular, disc-like, effluent, flow path and an annular series, of spaced apart, stationary, blades mounted on said tank in said eifiuent flow path, the combination of a relatively, narrow inner flat face on each said blade extending normal to the tangential discharge of, and coextensive in height with, the vanes of said impeller for partially checking the flow of said material; a pair of relatively wide, side faces on each said blade, each extending tangentially in the direction of, and parallel to, the tangential discharge of said vanes and co extensive in height therewith, and scrubbing means on each said side face for disintegrating lumps and fibre bundles in material moving along each opposite side face of said blades. i

2. A combination as specified in claim 1 wherein each said blade includes a free terminal end and a base end; said side faces diverge from said free end to said base end and said inner face increases in width from said free end to said base end. i

3. A combination as specified in claim 1 wherein said scrubbing means comprises a plurality of elongated, continuous, sharp edged ribs separated by elongated, contin-' uous grooves, said ribs and grooves extending transversely to the tangential discharge of said impeller vanesfor individually and successively intercepting material tangentially discharged therealong.

4. In a pulper of the type having a tank with a bottom and an upstanding side wall and an impeller mounted to rotate in a horizontal plane at the centre of said bottom, said'impeller having upstanding vanes tangentially discharging and, vertically circulating material in said tank, the combination of an annular series of spaced apart, stationary individual blades, fixed to and upstanding from, said bottom, said blades defining a circle around said impeller, in the flow path of material discharged by said impeller, each said blade having a pair of opposite, up-

standing side faces tangentially arranged for tangential.

material fiowthereby without deflection, each side face having a plurality of identical, upstanding, continuous serrations extending transversely to said tangential flow for intercepting material flowing therealong; an inner up-.

standing face proximate said vanes and an outer upstand- 5. In a pulper having a circulating impeller rotating in a horizontal plane proximate the bottom of the pulper for tangential material discharge, the combination of a plurality of stationary blades, upstanding from said pulper bottom and defining a circle around said impeller, each said blade having a pair of opposite side faces, each arranged to lie along the path of said tangential material discharge without deflecting the same and each said side face having a plurality of sharp edged, continuous upstanding ribs separated'by grooves, arranged to successively intercept material passing therealong in said tangential discharge path for scrubbing and distintegrating said material.

6. A pulper as specified in claim 5 wherein said side faces are angularly disposed to axial planes and each said face extends straight in its cross axial plane to tangentially receive and discharge said material.

Beers July 1, 1930 Danforth et al; Apr. 16,1963 

1. IN A PULPER OF THE TYPE HAVING A TANK, A MATERIAL CIRCULATING IMPELLER THEREIN HAVING VANES TANGENTIALLY DISCHARGING MATERIAL IN AN ANNULAR, DISC-LIKE, EFFLUENT, FLOW PATH AND AN ANNULAR SERIES OF SPACED APART, STATIONARY, BLADES MOUNTED ON SAID TANK IN SAID EFFLUENT FLOW PATH, THE COMBINATION OF A RELATIVELY, NARROW INNER FLAT FACE ON EACH SAID BLADE EXTENDING NORMAL TO THE TANGENTIAL DISCHARGE OF, AND COEXTENSIVE IN HEIGHT WITH, THE VANES OF SAID IMPELLER FOR PARTIALLY CHECKING THE FLOW OF SAID MATERIAL; A PAIR OF RELATIVELY WIDE, SIDE FACES ON EACH SAID BLADE, EACH EXTENDING TANGENTIALLY IN THE DIRECTION OF, AND PARALLEL TO, THE TANGENTIAL DISCHARGE OF SAID VANES AND CO-EXTENSIVE IN HEIGHT THEREWITH, AND SCRUBBING 